Re: Pancake Coil Formula (fwd)

---------- Forwarded message ----------
Date: Tue, 5 May 1998 23:34:09 EDT
From: Hollmike <Hollmike-at-aol-dot-com>
To: tesla-at-pupman-dot-com
Subject: Re: Pancake Coil Formula (fwd)

   The inductance formula for a flat spiral is similar to the single layer
helical coil.

 L = a^2*n^2/(8*a + 11*c)
where n = number of turns
a = the average radius
c = difference between the outer and inner radii.
all dimensions in inches

The accuracy is within 5% if C > 0.2a.  The accuracy  may be less if skin
effect or distributed capacitance is appreciable.

This came from "Electrical Engineer's Handbook", Communication Electronics,
Pender , McIlwain, 3rd edition,1945.

Hope this helps,
Mike Hollingsworth